X-ray radiographic experimental investigation of the reference level in hydrostatic level measurement systems for boiling water reactors

Hydrostatic level control is of high priority for normal operation safety of BWR-type reactors. For the prevention of undershooting the limiting values precise and secure measuring techniques are indispensable. Actually the filling level is determined form the hydrostatic pressure difference to a reference column. For the secure non-invasive detection of the phase boundary water/steam in inclined tubes the X-ray radiography has been chosen. The experiments were aimed to study possible geometric influences on the water/steam phase boundary. It was shown that the reference filling level is not significantly changed in spite of permanent phase transitions, provided an ideal mechanical construction of the system is given. Future experiments shall be focused on the analysis of interface behavior in case of non-ideal geometries (welds).